And there we see, as mentioned above:
ns1.googleghs.com
ns2.googleghs.com
ns3.googleghs.com
ns4.googleghs.com

In this example, "mydomain.com" was, apparently, setup originally to use "ns1.googleghs.com" (x 4) for domain DNS addressing. Apparently, until this week, the addressing worked - and Google was willing to host DNS addressing for some private domains.